Process for preparing the dialdehyde of vinylcyclohexene

ABSTRACT

Process for preparing the dialdehyde of vinylcyclohexene

The present invention relates to a process for preparing the dialdehydeof vinylcyclohexene.

US 2009/0171125 A1 describes a process for hydroformylation of cyclicolefins. Here, a Rh catalyst is used.

The present invention has the object of providing a novelhydroformylation process. The process here is to afford an increasedyield compared to the method known from the prior art.

This object is achieved by a process according to claim 1.

Process comprising the process steps of:

-   -   a) initially charging vinylcyclohexene;    -   b) adding a compound of formula (I):

-   -   where R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸ are selected from: —H,        —(C₁-C₁₂)-alkyl, -Ph;    -   c) adding a Pt compound capable of forming a complex;    -   d) adding an iodine compound;    -   e) feeding in CO and H₂;    -   f) heating the reaction mixture from a) to e), to convert the        vinylcyclohexene to the dialdehyde.

In this process, process steps a) to e) can be effected in any desiredsequence. Typically, however, CO and H₂ are added after the co-reactantshave been initially charged in steps a) to d).

It is also possible here for process steps c) and d) to be effected inone step, for example by adding PtI₂.

In one variant of the process, the Pt compound and the iodine compoundare added in one step, by adding PtI₂.

The expression (C₁-C₁₂)-alkyl encompasses straight-chain and branchedalkyl groups having 1 to 12 carbon atoms. These are preferably(C₁-C₈)-alkyl groups, more preferably (C₁-C₆)-alkyl, most preferably(C₁-C₄)-alkyl.

Suitable (C₁-C₁₂)-alkyl groups are especially methyl, ethyl, propyl,isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, 2-pentyl,2-methylbutyl, 3-methylbutyl, 1,2-dimethylpropyl, 1,1-dimethylpropyl,2,2-dimethylpropyl, 1-ethylpropyl, n-hexyl, 2-hexyl, 2-methylpentyl,3-methylpentyl, 4-methylpentyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl,2,2-dimethylbutyl, 1,3-dimethylbutyl, 2,3-dimethylbutyl,3,3-dimethylbutyl, 1,1,2-trimethylpropyl, 1,2,2-trimethylpropyl,1-ethylbutyl, 1-ethyl-2-methylpropyl, n-heptyl, 2-heptyl, 3-heptyl,2-ethylpentyl, 1-propylbutyl, n-octyl, 2-ethylhexyl, 2-propylheptyl,nonyl, decyl.

In one variant of the process, R¹ and R⁴ are —H.

In one variant of the process, R⁵, R⁶, R⁷, R⁸ are -Ph.

In one variant of the process, R² and R³ are —(C₁-C₁₂)-alkyl.

In one variant of the process, R² and R³ are —CH₃.

In one variant of the process, the compound (I) has the structure (1):

In one variant of the process, the Pt compound is selected from:Pt(II)I₂, Pt(IV)I₄, diphenyl(1,5-COD)Pt(11), Pt(II)(acac)₂,Pt(0)(PPh₃)₄, Pt(0)(DVTS) solution (CAS: 68478-92-2),Pt(0)(ethylene)(PPh₃)₂, tris(benzylideneacetone)Pt(0), Pt(II)(OAC)₂solution, Pt(0)(t-Bu)₂, Pt(II)(COD)Me₂, Pt(II)(COD)I₂, Pt(IV)IMe₃,Pt(II)(hexafluoroacetylacetonate)₂.

In one variant of the process, the Pt compound is selected from:Pt(II)I₂, Pt(II)(acac)₂.

In one variant of the process, the Pt compound is Pt(II)I₂.

In one variant of the process, the iodine compound is selected from:alkali metal halide, alkaline earth metal halide. NH₄X, alkylammoniumhalide, dialkyl halide, trialkyl halide, tetraalkyl halide,cycloalkylammonium halide.

In one variant of the process, the iodine compound is selected from:Pt(II)I₂, Lil.

In one variant of the process, PtI₂ is added in an amount, measured inmol % based on vinylcyclohexene, so that the value is in the range of0.1 mol % to 5 mol %.

In one variant of the process, PtI₂ is added in an amount, measured inmol % based on vinylcyclohexene, so that the value is in the range of0.1 mol % to 3 mol %.

In one variant of the process, PtI₂ is added in an amount, measured inmol % based on vinylcyclohexene, so that the value is in the range of0.1 mol % to 1 mol %.

In one variant of the process, this process comprises the additionalprocess step e′): e′) adding a solvent.

In one variant of the process, the solvent is selected from: THF, DCM,ACN, heptane, DMF, toluene, texanol, pentane, hexane, octane, isooctane,decane, dodecane, cyclohexane, benzene, xylene, Marlotherm, propylenecarbonate, MTBE, diglyme, triglyme, diethyl ether, dioxane, isopropanol,tert-butanol, isononanol, isobutanol, isopentanol, ethyl acetate.

In one variant of the process, the solvent is selected from: THF, DCM,ACN, heptane, DMF, toluene, texanol.

In one variant of the process, CO and H₂ are fed in at a pressure in arange from 1 MPa (10 bar) to 6 MPa (60 bar).

In one variant of the process, CO and H₂ are fed in at a pressure in arange from 1 MPa (20 bar) to 6 MPa (50 bar).

In one variant of the process, the reaction mixture is heated to atemperature in the range from 30° C. to 150° C.

In one variant of the process, the reaction mixture is heated to atemperature in the range from 80° C. to 140° C.

In one variant of the process, the process comprises the additionalprocess step g): g) converting the dialdehyde to the diol.

In one variant of the process, the conversion of the dialdehyde to thediol is carried out using “Shvo's catalyst” (CAS 104439-77-2).

In addition to the process, also claimed are the aldehyde mixture (2a)and (2b), and the alcohol mixture (3a) and (3b).

Aldehyde mixture comprising the compounds (2a) and (2b):

Alcohol mixture comprising the compounds (3a) and (3b):

The invention shall be elucidated in more detail hereinbelow withreference to a working example.

EXPERIMENTAL DESCRIPTION Conversion of Vinylcyclohexene to theDialdehyde

mmol of 4-vinylcyclohex-1-ene, 10 ml of absolute toluene, 0.5 mol %PtI₂, 2.2 equivalents of xantphos (1) (based on Pt) are placed underargon in a 25 ml steel autoclave from Parr Instruments. The autoclave ispressurized to 40 bar with synthesis gas (CO/H₂=1:1) and the reactionstarted by heating to 120° C. and stirring. This reaction is conductedat 40 bar/120° C. for 3.5 h. The autoclave is then cooled, the pressurereleased and a GC sample taken.

In a comparative experiment, Rh(acac)(CO)₂ was added instead of PtI₂.The reaction with Rh(acac)(CO)₂ ran over 11 h.

Yield of dialdehyde (2a)+(2b):

PtI₂: 92%

Rh(acac)(CO)₂: <14%

Conversion of the Dialdehyde to the Diol.

30 mmol of the isomeric mixture of the dialdehyde, 25 ml of absolutetoluene, 176 mg of “Shvo's catalyst” (CAS 104439-77-2) are transferredunder argon to a 100 ml Parr pressure autoclave. The autoclave ispressurized to 50 bar with hydrogen and the reaction carried out withstirring at 100° C. for 1 h and at 110° C. for a further 30 minutes. Thereaction is then discontinued (autoclave cooled and the pressurereleased). The reaction solution is transferred to a Schlenk vessel. Twophases are formed, the lower phase is isolated and freed of toluene invacuo. This gives the isomeric mixture of the diol (3a)+(3b).

Yield of diol (3a)+(3b): 85%

As the experimental results show, the object is achieved by the processaccording to the invention.

1. Process comprising the process steps of: a) initially chargingvinylcyclohexene; b) adding a compound of formula (I):

where R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸ are selected from: —H,—(C₁-C₁₂)-alkyl, -Ph; c) adding a Pt compound capable of forming acomplex; d) adding an iodine compound; e) feeding in CO and H₂; f)heating the reaction mixture from steps a) to e), to convert thevinylcyclohexene to the dialdehyde.
 2. Process according to claim 1,where R¹ and R⁴ are —H.
 3. Process according to claim 1, where R⁵, R⁶,R⁷, R⁸ are -Ph.
 4. Process according to claim 1, where R² and R³ are—(C₁-C₁₂)-alkyl.
 5. Process according to claim 1, where R² and R³ are—CH₃.
 6. Process according to claim 1, wherein the compound (I) has thestructure (1):


7. Process according to claim 1, wherein the Pt compound is selectedfrom: Pt(II)I₂, Pt(IV)I₄, diphenyl(1,5-COD)Pt(II), Pt(II)(acac)₂,Pt(0)(PPh₃)₄, Pt(0)(DVTS) solution (CAS: 68478-92-2),Pt(0)(ethylene)(PPh₃)₂, tris(benzylideneacetone)Pt(0), Pt(II)(OAC)₂solution, Pt(0)(t-Bu)₂, Pt(II)(COD)Me₂, Pt(II)(COD)I₂, Pt(IV)IMe₃,Pt(II)(hexafluoroacetylacetonate)₂.
 8. Process according to claim 1,wherein PtI₂ is added in an amount, measured in mol % based onvinylcyclohexene, so that the value is in the range of 0.1 mol % to 5mol %.
 9. Process according to claim 1, comprising the additionalprocess step e′): e′) adding a solvent.
 10. Process according to claim1, wherein the process comprises the additional process step g): g)converting the dialdehyde to the diol.
 11. Process according to claim10, wherein the conversion of the dialdehyde to the diol is carried outusing “Shvo's catalyst” (CAS 104439-77-2).
 12. Aldehyde mixturecomprising the compounds (2a) and (2b):


13. Alcohol mixture comprising the compounds (3a) and (3b):